### Rock mechanical failure characteristics and energy evolution …

For coal-rock combination with a dip angle of 30° and 45°, the compressive strength decreases until the ultimate compressive strength reaches the minimum …

اقرأ المزيدFor coal-rock combination with a dip angle of 30° and 45°, the compressive strength decreases until the ultimate compressive strength reaches the minimum …

اقرأ المزيدAt low confining pressures The Hock and Brown [2] criterion for the strength of a rock mass is as follows: 0.1 -- 0.3 /--m~3 ~ =___ s (1) O'c '~ 0.c where a~ = is the major principal stress at failure 0"3 = is the minor principal stress 0"c = is the uniaxial compression strength of the rock matrix m, s = are constants that depend on the ...

اقرأ المزيدThe uniaxial compressive strength of rock is one of the most important mechanical properties of rock and is widely used in rock foundation design, rock mass quality classification, and rock mass engineering stability analysis [1,2].The method of determining the uniaxial compressive strength of rocks by standard laboratory rock …

اقرأ المزيدHistorically, deep foundations in weak rock have been designed as friction elements using frictional resistance (fs), calculated from the unconfined compressive strength (UCS) of rock. Most of the published correlations of fs to UCS were developed based on load tests on low-capacity piles in specific geological conditions, using UCS …

اقرأ المزيد(10) can be written as follows: (11) q u = s 0.5 σ ci N σ As a result, the bearing capacity coefficient, N σ, depends on the HB parameter, s and the uniaxial compressive strength of the intact rock and can be written as: (12) N σ = q u s 0.5 σ ci Having the dimensionless coefficient N σ from Eq. (12), it is easy to calculate the ultimate ...

اقرأ المزيدstrength of rock is much smaller than the compressive or shear strength, tensile cracks often develop before com-pressive or shear failure. It is signiﬁcant for rock engi-neering to investigate the tensile behavior of rock. Mostly, rock bolts are used to improve the mechanical behavior of rock. Reinforcing the rock (rock mass) using

اقرأ المزيدThe compressive strength of the concrete cube test provides an idea about all the characteristics of concrete. By this single test one judge that whether Concreting has been done properly or not. Concrete compressive strength for general construction varies from 15 MPa (2200 psi) to 30 MPa (4400 psi) and higher in commercial and industrial ...

اقرأ المزيدAs it happens for other kinds of rock, a linear direct correlation has been found between uniaxial compressive strength and compressional wave velocity, as well as between dynamic and static Young ...

اقرأ المزيدThe strength of rock is generally described by a simple uniaxial compression test and although failure in this type of test may well be tensile it does not follow that the tensile strength of rock is closely correlated with its uniaxial compressive strength. A number of techniques [1-3] have been used to determine the tensile strength of coal.

اقرأ المزيدAbstract and Figures. Soft rock is a term that usually refers to a rock material with a uniaxial compressive strength (UCS) less than 20 MPa. This low strength range might be influenced by ...

اقرأ المزيد[5] ASTM-D7012-14 2014 Compressive Strength and Elastic Moduli of Inta ct Rock Core Specimens under Varying States of Stress ASTM pp 1 – 9 [6] C Chang, M D Zoback, and A Khaksar 2006 J. Pet. Sci ...

اقرأ المزيدThe strength of a rock is what prevents failure of the rock under external force, and it is one of the most important characteristics of the mechanical properties of a rock. The strength of a rock is usually expressed by peak stress and residual strength; the peak stress refers to the maximum load on the rock specimen during uniaxial or ...

اقرأ المزيدThe average compressive strength and standard deviation were found to be 15,707 psi and 398 psi, respectively. Analysis of the data proves that the compressive strength of marble is not influenced by steel end platen size or thickness. Similarly, low standard deviation and lack of trend occurred for the other three rock types.

اقرأ المزيدWhen used in its more precise sense, the term strength is usually qualified. Thus, the ultimate strength is the greatest stress difference that a test sample can support under given conditions of effective pressure, temperature, and strain rate (Handin, 1966; cf. Rock Deformation, Experimental; Rheology of Rocks).

اقرأ المزيدThe uniaxial compressive strength (UCS) is a mechanical property of intact rocks that is important in civil and mining engineering works (Aladejare 2020; Aladejare et al. 2020; Wang and Aladejare 2016a).Design and stability analysis of underground excavations and other geotechnical structures require the input of data like UCS on the …

اقرأ المزيدIt should be noted that although the theoretical ultimate compressive strengths of materials at different positions in the combination model under different rock-coal height ratios in Fig. 12 were obtained using the mechanical parameters of coal and rock materials in this study, these strength change trends are consistent for different coal and ...

اقرأ المزيدThe uniaxial compressive strength of a rock under static loading often decreases with an increasing temperature at which the rock has been heat-treated before strength testing. …

اقرأ المزيدCompressive strength refers to the ability of a certain material or structural element to withstand loads that reduce the size of that material, or structural element when applied. A force is applied to the top and …

اقرأ المزيدCompressive strength is an essential property in structural materials, for example, mortar, which comprises the interacial transtition zone in concrete, stone, and steel, since material design is normally evaluated in terms of the risk of compression failure. In addition the CBM is known as having strength for compression force. Therefore plenty of standard tests …

اقرأ المزيدThe compressive strength of a rock mass can be determined by in situ testing. Such tests are used in civil engineering and involve among others, plate bearing, hydraulic pressure chamber, flat ...

اقرأ المزيدcompressive strength of intact rock, the allowable pressure is taken as the uniaxial compressive strength. This correlation should be considered only as a first crude step in design (Peck 1976). 2. Strength of rock cores. A method for the assessment of the allowable bearing pressure is proposed by the Canadian Foundation Engineering

اقرأ المزيدThe ultimate compressive strength and corresponding failure strain are quantified. The test results show that Kalgoorlie basalt rock exhibits high sensitivity to strain rate effect on its compressive strength especially above 100/s and dynamic increment factor up to 2.3 at strain rate 403/s.

اقرأ المزيدBrown failure criterion for jointed rock masses is defined by: (1) where and are the maximum and minimum effective principal stresses at failure, is the value of the Hoek-Brown constant m for the rock mass, s and a are constants which depend upon the rock mass characteristics, and is the uniaxial compressive strength of the intact rock pieces. a

اقرأ المزيدEstimating compressive strength. General rock failure criterion can be reduced to a few parameters dependent on lithology (m) …

اقرأ المزيدThe difference in the unconfined compressive strength between. the slow and the rapid rates of loading for the rocks tested varied. considerably. The dynamic compressive strength factor f^ for the. granite was less than 1; for the basalt, 1.35; for the limestone, 1.52; and for the tuff, 1.74.

اقرأ المزيدUniaxial compressive strength (UCS) is a crucial mechanical parameter in the mining, construction, and petroleum industries. However, determination of the UCS is very tough, expensive, time-consuming, and destructive, requires expert workers for sample preparation, and cannot be determined in the field. As a result, prior researchers have …

اقرأ المزيدThe tensile strength of rock is defined as the pulling force, required to rupture a rock sample, divided by the sample's cross-sectional area. The tensile strength of rock is very small and is of the order of 0.1 times the compressive strength. Thus, a rock material is more likely to fail in tension than in compression.

اقرأ المزيدThe uniaxial compressive strength (UCS) is a mechanical property of intact rocks that is important in civil and mining engineering works (Aladejare 2020; Aladejare et …

اقرأ المزيدDeep underground rock tunnels and caverns in mountainous areas are often subjected to the coupling impacts of high geo-stresses and high-ground temperature that can threaten the stability of rock masses. This paper presents an experimental study of strength, deformation, and failure as well as energy evolution characteristics for …

اقرأ المزيدIt should be noted that although the theoretical ultimate compressive strengths of materials at different positions in the combination model under different rock …

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